update workflows to support alpha branches (#202)

Signed-off-by: Rajesh Hegde <[email protected]>

Author: irajeshegde

.github/workflows/docker-ci.yml

@@ -5,6 +5,7 @@ on:
     branches:
       - 'master'
       - 'experimental/*'
+      - '*alpha*'
     tags:
       - 'v*'
   pull_request: